Energy storage device

Abstract

An energy storage device comprises an energy storage tank containing an energy storage carrier and a coil pipe installed in the energy storage tank and used for allowing an energy transfer medium to go in and out, the coil pipe comprises a first straight pipe, a second straight pipe and a plurality of S-shaped pipes, and the first straight pipe and the second straight pipe are arranged in parallel in the vertical direction of the height of the energy storage tank; the multiple S-shaped pipes are vertically arranged to be parallel to the first straight pipe and periodically extend to the second straight pipe, every two adjacent S-shaped pipes in the multiple S-shaped pipes are staggered in the extending direction, and every two nearest S-shaped pipes which are separated are not staggered in the extending direction. The energy storage carriers with different heights in the energy storage tank can store energy uniformly during energy storage, and the temperatures of the energy transfer media in the S-shaped pipes are close during energy release, so that the temperature of the energy transfer media flowing out of the energy storage device through the second straight pipes is stable, the heat exchange stability is maintained, and the heat exchange efficiency is ensured.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an energy storage device. Background Art

[0002] In the current conventional energy storage devices, the S-shaped tubes in the energy storage tank are arranged in one or more layers in a transverse manner, and each layer of S-shaped tubes exchanges heat at different heights in the energy storage tank. Since the density of liquid increases at low temperatures, the liquid with high density will sink to the bottom of the energy storage tank under the action of gravity. Therefore, during the energy storage process, the temperature of the energy carrier at the bottom of the energy storage tank is lower than that of the upper energy carrier. The temperature of the energy carrier in the energy storage tank is uneven, so that during the heat exchange and energy release process, the energy transfer medium in each S-shaped tube absorbs different amounts of energy from the energy carriers at different heights in the energy storage tank. The temperature of the energy transfer medium flowing out of the outlet end of each layer of S-shaped tube is different, so that the temperature of the energy transfer medium flowing out of the energy storage device fluctuates, resulting in unstable heat exchange.

[0003] In addition, the ethylene glycol aqueous solution in the S-shaped tube of the existing energy storage device cools down the water in the energy storage tank to make ice. After the ice storage is completed, the water in the energy storage tank has been transformed from liquid to solid ice, which has very high mechanical strength and its volume will also increase by 3%-8%. Solid ice usually requires energy to be broken, and the ethylene glycol aqueous solution in the S-shaped tube transfers the cold energy to the air-conditioning system through a water pump and a plate heat exchanger for users to use. At the same time, small crushed ice has poor fluidity and is not easy to be converted and utilized. Summary of the invention

[0004] In order to solve the technical problems of unstable heat exchange and low heat exchange efficiency of existing energy storage devices, the present application provides an energy storage device, including an energy storage tank for accommodating an energy storage carrier and a coil installed inside the energy storage tank for the entry and exit of an energy transfer medium, the coil including a first straight tube, a second straight tube and a plurality of S-shaped tubes, the first straight tube and the second straight tube being arranged in parallel in a vertical direction of the height of the energy storage tank, the plurality of S-shaped tubes being respectively arranged vertically to extend in parallel and periodically from the first straight tube to the second straight tube, and two adjacent S-shaped tubes among the plurality of S-shaped tubes are staggered in the extension direction and the two nearest S-shaped tubes are not staggered in the extension direction.

[0005] According to the above technical solution, by vertically arranging multiple S-shaped tubes in the energy storage tank so that they extend parallelly and periodically from the first straight tube to the second straight tube, the energy transfer medium in each S-shaped tube exchanges energy with energy storage carriers at different heights in the energy storage tank. On the one hand, when storing energy, energy storage carriers at different heights in the energy storage tank store energy evenly. On the other hand, when releasing energy, the temperature of the energy transfer medium in each S-shaped tube is ensured to be similar. The temperature of the energy transfer medium flowing out of the energy storage device through the straight tube is stable, and two adjacent S-shaped tubes among the multiple S-shaped tubes are staggered in the extension direction and the two closest S-shaped tubes are not staggered in the extension direction, so that the energy transfer medium in the S-shaped tube and the energy storage carrier in the energy storage tank can exchange heat more evenly. Therefore, the energy storage device with the above structure can maintain heat exchange stability during the heat exchange process and ensure heat exchange efficiency.

[0006] In certain embodiments, the spacing between two adjacent S-shaped tubes in the plurality of S-shaped tubes is 20-30 cm, and can be 20 cm, 22 cm, 25 cm, 28 cm, 30 cm, and preferably 20 cm. The spacing between two adjacent S-shaped tubes is 20-30 cm, which can control the number of S-shaped tubes and thus control costs while ensuring heat exchange efficiency.

[0007] In certain embodiments, the bottom of each S-shaped tube in the plurality of S-shaped tubes at the height of the energy storage tank is adjacent to the bottom of the inner cavity of the energy storage tank, and the distance between the top and the top of the inner cavity of the energy storage tank is 1 / 8-1 / 4 of the height of the inner cavity of the energy storage tank, preferably 1 / 8. If the distance between the tops is too large, the heat exchange efficiency of the top energy storage carrier in the energy storage tank cavity is low, and if the distance is too small, the energy storage carrier in the energy storage tank freezes and expands, which can easily damage the energy storage device.

[0008] In certain embodiments, the distance between the two adjacent S-shaped tubes in the extension direction is the straight-line distance between adjacent wave crests and wave troughs of the same S-shaped tube in the extension direction, which can optimize the heat exchange uniformity between the energy transfer medium in the S-shaped tube and the energy storage carrier in the energy storage tank, further increasing the heat exchange efficiency.

[0009] In certain embodiments, the system further comprises a plurality of support plates vertically fixed in the energy storage tank, and the plurality of S-shaped tubes are respectively fixed in the energy storage tank through the support plates.

[0010] In certain embodiments, the wall of the energy storage tank includes an inner liner, an intermediate insulation layer, and a surface protection layer. The energy in the energy storage tank can be prevented from being lost by being transferred to the outside to the greatest extent. The inner liner of the wall of the energy storage tank can be a 304 stainless steel inner liner of 3-5 mm, the intermediate insulation layer can be a 5-10 mm polyurethane insulation layer, and the surface protection layer can be a 0.5 mm 304 stainless steel. An observation mirror for observing the liquid state in the energy storage tank cavity is also installed on the wall of the energy storage tank. The higher the height of the energy storage tank, the thicker the inner liner of the wall.

[0011] In certain embodiments, the energy storage carrier and the energy transfer medium are ethylene glycol aqueous solutions with different freezing points, and the freezing point of the energy transfer medium is lower than the freezing point of the energy storage carrier. The freezing point of ethylene glycol aqueous solution is lower than the freezing point of water, and the higher the concentration of ethylene glycol aqueous solution, the lower the freezing point. Using ethylene glycol aqueous solution with a low freezing point as an energy storage carrier can store more energy during the energy storage process.

[0012] In certain embodiments, the freezing point of the energy transfer medium is at least 15°C lower than the freezing point of the energy storage carrier, which can ensure that the energy transfer medium does not freeze or become viscous when the minimum cold load temperature is met during the cold storage process, and does not produce flocs due to low temperature, resulting in poor fluidity and causing the occurrence of selective failures such as excessive operating current of the water pump. During the cold storage process, the ethylene glycol aqueous solution in the energy storage tank can be kept in a semi-flowing ice slurry or micro-ice state, and more cold energy can be stored by phase change from solid to liquid.

[0013] In some embodiments, the inner surface and / or outer surface of the tube wall of the plurality of S-shaped tubes is a heat transfer layer formed by a superconducting coating or a heat transfer material. The superconducting coating or the heat transfer layer contains graphene or other high thermal conductivity materials. The superconducting coating can increase the heat transfer efficiency between the medium inside and outside the S-shaped tube. The material of the S-shaped tube is stainless steel or aluminum, aluminum alloy or other materials with good thermal conductivity.

[0014] The energy storage device of the present invention can be used for cold storage or heat storage. In some embodiments, the energy storage device is a cold storage device. In other embodiments, the energy storage device is a heat storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present application is further described below in conjunction with the accompanying drawings and embodiments. In the accompanying drawings:

[0016] Figure 1 It is a side view of the energy storage device;

[0017] Figure 2 It is the top view of the energy storage device;

[0018] Figure 3 This is a structural diagram of the energy storage air conditioning system.

[0019] Description of reference numerals:

[0020] 10 energy storage device; 101 energy storage tank; 1011 stainless steel surface protection layer; 1012 polyurethane insulation layer; 1013 stainless steel liner; 1014 observation mirror; 102 coil; 1021 S-shaped tube; 1022 first straight tube; 1023 second straight tube; 103 support plate; 20 refrigeration unit; 30 cooling tower; 40 cold storage heat exchanger; 50 air-cooled heat pump unit; 60 heat storage heat exchanger; 70 refrigeration / cold exchange conversion three-way valve; 80 cold storage / heat storage conversion water valve; 90 winter and summer conversion electric valve; 100 heat storage / heat dissipation conversion electric valve. DETAILED DESCRIPTION

[0021] The technical solution of the present application will be described in detail below in conjunction with the accompanying drawings and embodiments, but the present application is not limited to the scope of the embodiments.

[0022] Example 1

[0023] like Figure 1 and Figure 2 As shown, the energy storage device 10 includes an energy storage tank 101 for accommodating an energy storage carrier and a coil 102 installed in the energy storage tank 101 for the energy transfer medium to enter and exit.

[0024] The wall of the energy storage tank 101 includes a 3 mm 304 stainless steel inner liner 1013, a 5 mm polyurethane insulation layer 1012, and a 0.5 mm 304 stainless steel surface protection layer 1011. An observation mirror 1014 for observing the liquid state in the energy storage tank is also installed on the energy storage tank 101. The height of the energy storage tank 101 is 80 cm.

[0025] The coil 102 includes a first straight tube 1022, a second straight tube 1023 and a plurality of S-shaped tubes 1021. The first straight tube 1022 and the second straight tube 1023 are arranged in parallel in the vertical direction of the height of the energy storage tank 101. The inlet tube of the coil 102 (the first straight tube 1022) and the outlet tube of the coil 102 (the second straight tube 1023) are respectively located on opposite sides of the bottom of the energy storage tank 101. The plurality of S-shaped tubes 1021 are respectively arranged vertically to extend from the first straight tube 1022 to the second straight tube 1023 in parallel and periodically, and two adjacent S-shaped tubes 1021 are staggered in the extension direction and the two nearest S-shaped tubes 1021 are not staggered in the extension direction. The distance between the two adjacent S-shaped tubes 1021 in the extension direction is the straight-line distance between the adjacent wave crests and wave troughs of the same S-shaped tube 1021 in the extension direction.

[0026] The spacing between two adjacent S-shaped tubes 1021 in the plurality of S-shaped tubes 1021 is 20 cm. The bottom of each S-shaped tube 1021 is adjacent to the bottom of the inner cavity of the energy storage tank 101 at the height of the energy storage tank 101, and the distance between the top and the top of the energy storage tank 101 cavity is 1 / 8 of the height of the energy storage tank 101, that is, the distance between the top of the S-shaped tube 1021 and the top of the energy storage tank 101 cavity is 10 cm. The S-shaped tube 1021 is fixed in the energy storage tank 101 by a plurality of support plates 103 vertically fixed in the energy storage tank 101. The inner and outer surfaces of the tube walls of the plurality of S-shaped tubes 1021 are superconducting coatings containing graphene.

[0027] The energy storage tank 101 uses an ethylene glycol aqueous solution with a freezing point of -20°C as the energy storage carrier, and the S-shaped tube 1021 uses an ethylene glycol aqueous solution with a freezing point of -38°C as the energy transfer medium.

[0028] During the cold storage process, the energy transfer medium at -20 to -28°C enters the first straight tube 1022, and then enters each S-shaped tube 1021 to transfer the cold to the high freezing point energy carrier in the energy storage tank 101, and then flows out of the energy storage device 10 through the outlet of the second straight tube 1023, and the cold is continuously transferred to the energy storage carrier in the energy storage tank 101 in this cycle. When the temperature of the energy storage carrier in the energy storage tank 101 reaches 2°C below the freezing point (at this time, the energy storage carrier in the energy storage tank 101 is in an ice slurry state) or after the low electricity price period ends, the energy storage is stopped. During the energy discharge process, the high temperature energy transfer medium in the S-shaped tube 1021 flows into the first straight tube 1022 and then enters the S-shaped tube 1021 to absorb the cold of the low temperature energy storage carrier in the energy storage tank 101. The cooled energy transfer medium flows out of the energy storage device 10 through the outlet of the second straight tube 1023, and the cold is transferred to the air conditioning system for use in this cycle.

[0029] During the heat storage process, the high-temperature energy transfer medium enters the first straight tube 1022, then enters each S-shaped tube 1021 to transfer heat to the energy storage carrier in the energy storage tank 101, and then flows out of the energy storage device 10 through the outlet of the second straight tube 1023, and the heat is continuously transferred to the energy storage carrier in the energy storage tank 101 in this cycle. After the low electricity price period, the low-temperature energy transfer medium in the S-shaped tube 1021 flows into the first straight tube 1022 and then enters the S-shaped tube 1021 to absorb the heat of the high-temperature energy storage carrier in the energy storage tank 101. The heated energy transfer medium flows out of the energy storage device 10 through the outlet of the second straight tube 1023, and the heat is transferred to the air conditioning system for use in this cycle.

[0030] Example 2

[0031] like Figure 3As shown, in the cold storage stage of the energy storage air conditioning system, the compressor of the refrigerating unit 20 is started. The heat generated by the refrigerating unit 20 during refrigeration is transported to the cooling tower 30 through the cooling water pump via the pipeline with tap water as the carrier (since the low electricity price period is mostly late at night, the unit is operated at night, and the cooling tower has a better heat dissipation effect than during the day), and the heat generated by the refrigerating unit 20 is dissipated into the air through the cooling fan. After the heat is dissipated, the cooling water returns to the refrigerating unit 20 through the pipeline to exchange heat to form a closed loop through the cooling water pump. The energy transfer medium 45%-59% ethylene glycol aqueous solution (freezing point temperature is about -38°C) sends the cold energy generated by the operation of the refrigerating unit 20 into the first straight pipe 1022 of the energy storage device 10 through the water pump and the pipeline, and then reaches each S-shaped pipe 1021 to transfer the cold energy to the energy storage carrier 30% ethylene glycol aqueous solution (freezing point temperature is -20°C) in the energy storage tank 101. After transferring the cold, the energy transfer medium flows out of the energy storage device 10 through the outlet of the second straight pipe 1023 and returns to the refrigeration unit 20 to take away the cold. This process is repeated to cool the energy storage carrier in the energy storage tank 101 to -22°C to form an ice slurry. When the energy storage carrier in the energy storage tank 101 reaches an ice slurry state or the electricity price valley period ends, the refrigeration unit 20 stops refrigeration. The energy transfer medium is regulated by the refrigeration / cold exchange conversion three-way valve 70 so that it no longer passes through the refrigeration unit 20 and stops storing energy. During the energy release process, the high-temperature energy transfer medium enters the S-shaped tube 1021 through the first straight pipe 1022 to absorb the cold of the low-temperature energy storage carrier in the energy storage tank 101. The cooled energy transfer medium flows out through the outlet of the second straight pipe 1023, takes the cold out of the energy storage device 10 and transfers it to the air-conditioning chilled water circuit through the cold storage heat exchanger 40, providing a cold source for the air-conditioning system.

[0032] In the heat storage stage, the heat storage path is connected by adjusting the winter-summer conversion electric valve 90 and the cold storage / heat storage conversion water valve 80 to control the flow of the energy transfer medium in the heat storage system. The energy transfer medium transfers the heat generated by the air-cooled heat pump unit 50 to the energy transfer medium in the S-shaped tube 1021 through the heat storage heat exchanger 60, and the energy transfer medium further transfers the heat to the energy storage carrier in the energy storage tank 101. After the energy storage is completed, the heat storage / heat dissipation conversion electric valve 100 is switched to connect the heat dissipation path, and the energy transfer medium no longer transfers heat to the energy storage device 10 through the heat storage heat exchanger 60. The low-temperature energy transfer medium enters the S-shaped tube 1021 through the first straight tube 1022 to absorb the heat of the high-temperature energy storage carrier in the energy storage tank 101, and then flows out through the outlet of the second straight tube 1023, taking the heat out of the energy storage device 10 and transferring it to the air conditioning hot water circuit through the heat storage heat exchanger 60, providing a heat source for the air conditioning system.

[0033] In summary, the present application sets a plurality of parallel vertically arranged S-shaped tubes in the energy storage tank of the energy storage device, wherein two adjacent S-shaped tubes among the plurality of S-shaped tubes are staggered in the extension direction and the two nearest S-shaped tubes are not staggered in the extension direction, so that energy storage carriers of different heights in the energy storage tank store energy evenly during energy storage, and the temperature of the energy transfer medium in each S-shaped tube is similar during energy release, so that the temperature of the energy transfer medium flowing out of the energy storage device through the second straight tube is stable, thereby maintaining heat exchange stability and ensuring heat exchange efficiency.

[0034] The above is only an embodiment of the present application, which is only used to help understand the present application and is not used to limit the protection scope of the present application. It should be pointed out that for those skilled in the art, several improvements made without departing from the principle of the present application should also be regarded as the protection scope of the present application.

Claims

1. An energy storage device, comprising an energy storage tank for accommodating an energy storage carrier and a coil installed inside the energy storage tank for energy transfer medium to enter and exit, characterized in that: The coil includes a first straight tube, a second straight tube and a plurality of S-shaped tubes, wherein the first straight tube and the second straight tube are arranged in parallel in the vertical direction of the energy storage tank height, and the plurality of S-shaped tubes are respectively arranged vertically to extend from the first straight tube in parallel and periodically to the second straight tube, and two adjacent S-shaped tubes among the plurality of S-shaped tubes are staggered in the extension direction and the two nearest S-shaped tubes are not staggered in the extension direction.

2. The energy storage device according to claim 1, characterized in that: The distance between two adjacent S-shaped tubes in the plurality of S-shaped tubes is 20-30 cm.

3. The energy storage device according to claim 1, characterized in that: The bottom of each of the multiple S-shaped tubes at the energy storage tank height is adjacent to the bottom of the energy storage tank inner cavity, and the distance between the top and the top of the energy storage tank inner cavity is 1 / 8-1 / 4 of the height of the energy storage tank inner cavity.

4. The energy storage device according to claim 3, characterized in that: The distance between the top of each S-shaped tube in the plurality of S-shaped tubes at the height of the energy storage tank and the top of the inner cavity of the energy storage tank is 1 / 8 of the height of the inner cavity of the energy storage tank.

5. The energy storage device according to claim 1, characterized in that: The distance between the two adjacent S-shaped tubes in the extension direction is the straight-line distance between adjacent wave crests and wave troughs of the same S-shaped tube in the extension direction.

6. The energy storage device according to claim 1, characterized in that: It also includes a plurality of support plates vertically fixed in the energy storage tank, and the plurality of S-shaped tubes are respectively fixed in the energy storage tank through the support plates.

7. The energy storage device according to claim 1, characterized in that: The wall of the energy storage tank comprises an inner liner, an intermediate heat-insulating layer and a surface protection layer.

8. The energy storage device according to claim 1, characterized in that: The energy storage carrier and the energy transfer medium are ethylene glycol aqueous solutions with different freezing points, and the freezing point of the energy transfer medium is lower than the freezing point of the energy storage carrier.

9. The energy storage device according to claim 8, characterized in that: The freezing point of the energy transfer medium is at least 15° C. lower than the freezing point of the energy storage carrier.

10. The energy storage device according to any one of claims 1 to 9, characterized in that: The inner surface and / or outer surface of the tube wall of the plurality of S-shaped tubes is a superconducting coating.

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